The present invention relates generally to methods of manufacturing a transistor, and more specifically, to a method of reducing oxygen migration into a high-k dielectric layer of a transistor during manufacture of the transistor.
In various high-k metal gate (HKMG) transistors, a source and a drain are built into a substrate and a gate structure is built on top of the substrate. The gate structure includes gate material in a gap between flowable oxide materials built on top of the substrate. The gap is generally lined with a high-k dielectric material. However, since the high-k dielectric material is in contact with the top surfaces of the flowable oxide material during a manufacturing stage, oxygen molecules can migrate from the flowable oxide material into the high-k dielectric material. Once inside the high-k dielectric material, the oxygen can affect the performance of the resulting HKMG transistor. Therefore, there is a desire to reduce or prevent migration of oxygen atoms into the high-k dielectric layer of the gate structure.